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M Friedrich

Publications and source records attributed to M Friedrich.

At least 181 records · Page 10Linked to original sources
PubMed1993

[Progress in mammography technics. Bimetal anode tubes and selective filtration technic].

The use of molybdenum (Mo) as material for anodes and filters in mammography has been a result of contrast optimisation for breasts of low to medium radiation absorption. To penetrate denser breasts the kV must be increased, thus increasing the fraction of the harder radiation component and deteriorating image contrast. Besides this an increased radiation exposure to the patient must be accepted. In these cases the flexible use of rhodium (Rh) as anode and filter material is promising. A newly developed mammographic equipment (Senographe DMR, General Electric-CGR) offers these features. With selective rhodium filtering and anode material our measurements confirm a reduced radiation exposure (less than 50%) in dense breasts with significantly improved image contrast compared with the conventional molybdenum technique.

Equipment Design↗
PubMed1993

Voltage-dependent kinetics of Na-Ca exchange current in Ca(2+)-loaded guinea pig heart cells.

Voltage-dependent properties of Na-Ca exchange current were revealed with the patch-clamp technique in Ca(2+)-overloaded guinea pig ventricular myocytes in the whole cell configuration. With the assumption that the transient inward current (Iti) is mediated by the Na-Ca exchanger, oscillations of internal Ca2+ concentration ([Ca2+]i) were used to investigate voltage-dependent kinetics of exchange current differences at two [Ca2+]i values. After Iti was elicited by clamping from -45 mV to basic pulses of +10 mV, pairs of equipotential short test pulses were applied during the basic pulse at both the phase of low [Ca2+]i (between two neighboring Iti values) and the phase of high [Ca2+]i (at the peak of Iti). The test pulses were short enough to leave the time course of Iti during the basic pulse approximately unchanged, which allowed study of the voltage dependence of the respective current differences without disturbing the underlying oscillation of [Ca2+]i. The current differences were inward at all potentials between -140 and +70 mV, started from an equal initial value, and obeyed characteristic voltage-dependent time courses: hyperpolarization to potentials negative to -70 mV caused an initial current increase, which was followed by a decay to very small amplitudes or zero with a decay time constant decreasing toward hyperpolarization e-fold per 45.6 mV. Depolarizing pulses caused a decay of the current differences to smaller levels. Respective current differences formed during a slowly decaying current component, following the Ca current spike, showed equal voltage-dependent properties. This indicates that the slowly decaying current component is preferentially also carried by the Na-Ca exchanger.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[Hemodilution].

Explore the source record for details and available documents.

Contraindications↗
PubMed1993

[Granulomatous mesenteritis in CT].

The authors report on the clinical pattern of symptoms and on conventional and CT diagnostics of a granulomatous mesenteritis. The differential diagnoses are discussed.

Diagnosis, Differential↗
PubMed1993

[The technique and results of mammography].

In the field of mammography, technical progress has been achieved and successfully implemented in routine practice in the last few years. The diagnostic value of mammography has been re-assessed in numerous studies. Breast conserving therapy of breast carcinoma has posed new pre- and postoperative diagnostic tasks. The introduction of mammography into a future national breast cancer detection program will present a challenge for many mammographers in several aspects. Radio-epidemiological doubts about introduction of mammographic screening are in-substantial.

Breast Diseases↗
PubMed1992

[Rhabdomyolipoma of the right ventricle].

Echocardiography on a 29-year-old woman with exercise-unrelated tightness in the left chest for some months demonstrated an echo-dense space-occupying lesion in the outflow tract of the right ventricle (RV). Nuclear magnetic imaging revealed an ovular, fat-containing tumour, 3 x 2 x 2 cm in size. Because of threatened obstruction of the RV outflow tract removal of the tumour under cardiopulmonary bypass was undertaken. But complete removal was possible only by resecting a 2 x 3 cm area of the anterior wall of the RV, the resulting defect being covered with a Goretex patch. Histological examination identified the tumour as a rhabdomyolipoma. The patient was free of symptoms 1 year postoperatively.

Adult↗
PubMed1992

Transport of L-leucine hydroxy analogue and L-lactate in human small intestinal brush border membrane vesicles.

Nitrogen load can be reduced by substituting dietary protein intake with keto or hydroxy analogues of amino acids. To investigate their intestinal absorption, human jejunal brush border membrane vesicles were used to measure uptake of L-leucine hydroxy analogue (L-LHA) and L-lactate. Uptake assays were performed under voltage-clamped conditions in the presence of valinomycin and K+ inside and outside. Both inward directed H(+)- and Na(+)-gradients stimulated uptake of both substrates. The H(+)-gradient was the major driving force and led to an increased rate of L-LHA or L-lactate transport. The proton ionophore FCCP abolished the H(+)-gradient-driven but not the Na(+)-gradient-driven uptakes of both substrates. The H(+)-gradient-driven uptake of both substrates was trans-stimulated by L-LHA, D-LHA, L-valine hydroxy analogue or L-lactate, respectively. In the presence of a Na(+)-gradient the uptake of tracer L-lactate was trans-stimulated only after preloading the vesicles with L-lactate but not by L-LHA. It can be concluded that the H(+)-gradient-driven transport of L- or D-hydroxy analogues of branched chain amino acids and L-lactate across the human intestinal brush border membrane is mediated by the same carrier.

Biological Transport, Active↗
PubMed1992

Anoxia induces time-independent K+ current through KATP channels in isolated heart cells of the guinea-pig.

1. Isolated ventricular heart cells of the guinea-pig were exposed to anoxia (PO2 < 0.1 Torr) which induced a time-independent K+ current. This current was studied with the patch clamp technique in the whole-cell and cell-attached configuration. 2. The latency until anoxia-induced changes of whole-cell current developed was distributed exponentially (mean 10.5 min; n = 41). The current was abolished within 2-4 s of reoxygenation. 3. The reversal potential of the anoxia-induced change of whole-cell current at 5.4 and 15 mM [K+]o was -82 and -61 mV, respectively. 4. Analysis of current noise in whole-cell current during the phase of the slow development of the anoxia-induced current yielded a slope conductance of unitary currents of 8.1 pS (5.4 mM [K+]o) which is far below the 30 pS of KATP channels in inside-out patches with no Na+ and Mg2+ in the bath. 5. Reduced unitary current induced by anoxia was recorded in single-channel measurements with 10.4 mM-K+ in the pipette. 6. Using 150 mM-K+ in the pipette, anoxia caused unitary inward currents with a slope conductance of 83 pS. The open probability of the channels (P(o)) reached maximum values between 0.6 and 0.95. The channels closed within 1-3 s of reoxygenation. 7. At voltages between -85 and -45 mV and maximum P(o), open time histograms were dominated by a fast exponential (tau 01 = 0.55 +/- 0.21 ms, mean +/- S.D.) and one or two slow exponentials. 8. Voltage ramp experiments showed that single-channel currents were slightly rectifying in the inward direction. 9. Glibenclamide (1 microM) reversibly blocked the anoxia-induced whole-cell and single-channel currents. 10. It is concluded that during anoxia it is only KATP channels which open by a sufficient decrease of submembrane ATP levels.

Action Potentials↗
PubMed1992

Value of computer tomography in the detection of bullae and blebs in patients with primary spontaneous pneumothorax.

In this prospective study, the value of computed tomography (CT) in detecting bullae and bleb formation of the lung in 35 patients with primary spontaneous pneumothorax (PSP) has been determined. The ability of CT in the detection of bullae and bleb formation and fibrotic changes is compared with the chest film in PSP. CT showed pathological lung changes in 31/35 patients. In most cases, few (n < 5) and small blebs (i.e., < 2 cm in diameter) were found. In 16/35 cases, blebs (< 2 cm) and bullae (> 2 cm in diameter) occurred in the extra-apical region. Contralateral pathological changes were found in 23/35. Bullae (> 2 cm) could be detected only in 6/35. In the chest film, bullae and blebs could be detected in 11/35 cases on the ipsilateral (in 2/35 cases not confirmed by CT), in 3/35 on the bilateral and in 4/35 only on the contralateral side. Thus, CT was proved to be of high value in the assessment of bullae and bleb formation in PSP compared with chest film. Negative pressure drainage was instituted as primary therapy. In a follow-up of 9.6 (+/- 5.7 SD) months, only early recurrences were noticed (n = 35). The rate of recurrences was 6/35 patients. The longer follow-up period (mean 31.7 +/- 6.1 months) could be performed for 32 patients; 3 were lost. Additionally, 2 recurrences occurred. No correlation between recurrences and anatomical status (number, size and distribution of blebs/bullae) as assessed by CT was found. Differential treatment protocols on the basis of the initial findings do not appear to be warranted.

Adolescent↗
PubMed1992

Level of cortisol and reactivity of adrenal cortex to exogenous ACTH at neonatal period in calves.

The studies were carried out on calves from 1st to 21st day of life. Cortisol level and reactivity of adrenal cortex to exogenous ACTH were analysed. The highest level of cortisol in blood was observed in first days of life in the calves. Then the level became considerably decreased. In the experimental group two subgroups differing in cortisol level were distinguished. High or low level occurred on the first day and the difference kept over two weeks of their life. Adrenal cortex just on the day of birth showed full functional maturity of molecular receptors binding ACTH.

Adrenal Cortex↗
PubMed1992

[The problem of diffuse cranial hyperostosis following cerebral trauma in early childhood--a case report].

This is a report on an uncommon case of cranial hyperostosis with generalised considerable thickening of the calvarium. As a consequence of a cerebral trauma in early childhood the patient developed an intracerebral haematoma. Subsequently a disturbance of brain growth with posttraumatic, symptomatic epilepsy was noted. The anticonvulsant long-term treatment was mainly based on dilantin (diphenylhydantoin). Two different reasons for the distinct skull changes in the present case must be taken into consideration. Firstly, a widening of the dipole induced by dilantin, and secondly, a compensatory thickening of the vault with alterations of the skull base as seen in cerebral atrophy or after relieved hydrocephalus. These mechanisms are discussed with regard to the relevant literature.

Brain Injuries↗
PubMed1992

[Focal spot sizes and the geometric unsharpness of mammographic equipment].

The visibility of microcalcifications in mammography is limited, inter alia, by the dimensions of the focal spot of the x-ray tube. The user should be able to evaluate a given nominal value of the focal spot and to assess the effective size of the focal spot in his x-ray tube. Determination of the resolution with the help of the mammographic phantom suggested by the German DIN standards specifications requires special care. In the framework of the German Mammography Study, 45 mammography devices at different locations were tested with regard to their focal spot sizes. All devices complied with the acceptance test without any adverse comment, although--if judged objectively--only half of them have the resolution demanded by DIN standards. Consequently, in most of the cases the users are unaware of this, and the negative effects on the visibility of possibly present microcalcifications are often underestimated. The diagnostic importance of microcalcifications for the detection of breast cancer suggests, however, to abstain from devices which are only of limited usefulness in relevant mammography screening.

Calcinosis↗